Background. A key aspect in prevention of thromboembolic complications associated with atrial fibrillation (AF) is the use of anticoagulation therapy, specifically warfarin. Warfarin sensitivity considerably varies in different patients. Aim. To specify effects of different allele variants of genotype in combination with clinical factors on the pattern of adjusting the warfarin therapy in patients with non-valvular AF. Materials and methods. The study included patients with AF who were residents of the Saratov city. Results. Therapeutic doses of warfarin were related with GGCX и CYP2C9*2 gene polymorphisms in residents of the Saratov region. This finding is consistent with results of studies on other populations. Duration of warfarin dose adjustment significantly correlated with VKORC1, CYP4F2 and CYP2C9*3 gene polymorphisms. Furthermore, the highest significance was observed for the combination effect of gene allele variants and such clinical characteristics as history of MI, amiodarone therapy and smoking. Conclusion. In adjusting the warfarin dose, both pharmacogenetic and clinical characteristics of the patient and, most important, their combination effect, should be taken into consideration.